Needle guards

ABSTRACT

A needle guard ( 1 ) based upon a canting plate ( 6 ) becomes lockingly engaged with the needle ( 2 ) shaft both upon retraction of the needle tip within the guard ( 1 ), and upon any attempt to cause the needle tip to reemerge from the guard ( 1 ). The plate ( 6 ) is positioned to rotate into locking engagement with the shaft of the needle ( 2 ) both when an attempt is made to further withdraw the needle from the needle guard ( 1 ) and when an attempt is made to cause the needle tip to reemerge from the needle guard ( 1 ).

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. patent application Ser. No.10/905,884 filed Jan. 25, 2005 and U.S. Provisional Application No.60/544,352, filed Feb. 17, 2004, the disclosures of which areincorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to the field of medical devices. In particular,it relates to providing protection for “sharps” such as needles andwires that have been used on a subject and require provision to preventpersonnel from receiving a puncture wound from the used device that maygive rise to a risk of infection for such personnel. As such, theinvention may be characterized as a “needle guard” although it isintended to apply equally to any sharp device akin to a needle or wirethat requires protection.

BACKGROUND OF THE INVENTION

U.S. Pat. No. 6,280,419 describes a needle guard device thatautomatically engages with a needle when the tip of the needle iswithdrawn into an enclosing volume or cavity contained within theprotective device. The mechanism within the needle guard for engagingwith the needle operates on the principle of a canting plate that has ahole through which the shaft of the needle passes. Before deployment ofthe guard, the plate carrying the hole is oriented perpendicularly tothe axis of the needle shaft, and a tight sliding fit exists between theneedle shaft and the perimeter of the hole. Once the tip of the needlehas been withdrawn into the guard, the plate is caused by a spring to“cant” or rotate from its perpendicular orientation with respect to theneedle shaft. By reason of the tight sliding fit between the shaft andthe hole in the canting plate, the edge of the perimeter of the holeforcefully engages with the surface of the needle, preventing furtherretraction of the needle in the direction that would cause the cantingplate to cant at an even further angle.

In the design of the needle guard of U.S. Pat. No. 6,280,419, thecanting plate acts to arrest the needle shaft against further withdrawalof the needle shaft through the needle guard's cavity. The cantingaction described above occurs when the needle tip has been withdrawninto the cavity and a sensing arm connected to the canting plate is ableto shift its position due to the retraction of the needle tip past anopening in a limb of the sensing arm through which the needle passesprior to the initiation of locking action.

In the specific design of the referenced patent, provision is made for awire to be present, passing through the core of the needle and the bodyof the needle guard. As the needle guard and needle are retracted, theyslide along this wire. To permit such movement to continue after theneedle tip has entered within the cavity of the needle guard, theopening in the limb on the sensing arm is in the form of a slot. Thebottom of the slot is large enough to permit passage of the needle shaftbefore the needle guard is deployed. The slot above the bottom is of areduced width, sufficient to allow passage of the wire, but narrowenough to prevent the reemergence of the needle tip from the needleguard, once the needle tip has withdrawn from the hole in the limb ofthe sensing arm. The reemergence of the needle is prevented in thisdesign by the presence of the sides of the limb on the sensing arm thatdefine the borders of the slot. These sides remain in the path that theneedle tip would have to follow if it were to attempt to re-emerge fromthe needle guard.

This system for preventing reemergence of the needle tip from the needleguard depends critically upon the engagement of the sidewall of theneedle with the sides of the slot in the locking limb on the sensingplate. As the needle wall is of a relatively small thickness, thismethod for preventing reemergence of the needle tip does not providemaximum reliability.

The present invention provides a system for preventing reemergence ofthe needle tip which is an alternative to, and may be more reliablethan, the system described above.

The invention in its general form will first be described, and then itsimplementation in terms of specific embodiments will be detailed withreference to the drawings following hereafter. These embodiments areintended to demonstrate the principle of the invention, and the mannerof its implementation. The invention in its broadest and more specificforms will then be further described, and defined, in each of theindividual claims which conclude this Specification.

SUMMARY OF THE INVENTION

The invention in one aspect is directed to a needle guard having acontainment case through which a needle projects. Within a cavity withinthe case, there is a canting plate having an aperture such as a hole,through which the needle projects, such hole having an inner facesurface bounded by first and second circumferential edges that provide aclose sliding fit around the needle. An alignment means in the form of asensing arm coupled to the canting plate is provided to align thecircumferential edges for sliding engagement with the needle while theneedle tip protrudes from the containment casing. Resilient biasingmeans act between the casing and the sensing arm to cause the cantingplate to rotate with respect to the needle upon withdrawal of the needletip into the containment cavity. This rotation occurs once the needletip has been withdrawn past a sensing limb on the sensing arm that may,optionally, contain a slot, hole, or other opening. The canting of thecanting plate causes the first and second circumferential edges boundingat the hole in the canting plate to be directed into locking engagementwith the surface of the needle shaft.

The canting plate is aligned within the cavity for connection betweenfirst and second pressure points connected to the canting plate andfirst and second abutment means present and carried within the cavity ofthe containment case. The first pressure point is positioned to engagewith the first abutment means upon withdrawal of the needle tip into theneedle guard cavity, such engagement effecting the canting of thecanting plate to resist further withdrawal of the needle once the tip iswithin the needle guard. The second pressure point is positioned toengage with the second abutment means once the canting plate has assumeda canted orientation whereby, upon any attempt to cause reemergence ofthe needle tip from the needle guard, contact between the secondpressure point and second abutment means tends to rotate the cantingplate so as to further engage the circumferential edges with the surfaceof the needle shaft.

Thus attempted advancement of the needle in either direction withrespect to the containment case, once the canting plate is canted withrespect to the needle, causes pressure to be applied through either ofthe pressure points by the abutment means to effect further lockingengagement of the circumferential edges with the surface of the needle.The result is to lockingly contain the needle tip within the containmentcase against either further withdrawal of the needle or reemergence ofthe needle.

The sensing arm serves as an alignment means for the canting plate towhich it is connected. These parts rotate in unison. Extending from thecanting plate, the sensing arm contains a limb which, through a hole,slot or finger, bears against the side of the needle or needle shaftwhile the needle tip protrudes from the containment casing. So long asthe limb on the sensing arm bears against the needle shaft, the cantingplate cannot rotate with respect to the needle. Upon retraction of theneedle tip past this limb of the sensing arm, the limb, the sensing armand the connected canting plate are free to rotate, allowing the cantingplate to take up a canting orientation that permits locking engagementof the needle guard with the needle.

The limb on the sensing arm may be in the form of an extension to thesensing arm that includes a plate with a hole or slot positioned anddimensioned to receive the needle therethrough before the needle iswithdrawn into the needle guard. Or it may simply comprise a finger thatprevents displacement of the limb and sensing arm so long as the fingerbears against the needle shaft.

As a supplemental protection against reemergence of the needle from theneedle guard case, a barrier portion of the limb may be extended belowthe hole or slot formed therein, such barrier portion resting in thepath of the needle when the canting plate has assumed a lockingorientation.

By further variation of the invention, an alternate supplementalreemergence barrier may be carried on a separate biased supportingmember with a sensing surface. This separate supporting member iscarried by the containment case, preferably on the opposite side of theneedle to the sensing arm of the locking plate. When the needle tip isdrawn past a separate barrier sensing surface, the biased supportingmember urges the reemergence barrier into the path of the needle,thereby preventing reemergence of the needle.

The needle guard according to the invention may be employed with orwithout the presence of a wire passing through the core of the needle.Thus the needle guard of the invention is suited for incorporation withthe designs of U.S. Pat. Nos. 5,458,658; 5,611,781 and 5,662,610 toSircom, as well as with other designs that rely upon the effect of acanting plate.

The foregoing summarizes the principal features of the invention andsome of its optional aspects. The invention may be further understood bythe description of the preferred embodiments, in conjunction with thedrawings, which now follow.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with the general description of the invention given above andthe detailed description of the embodiments given below, serve toexplain the principles of the present invention.

FIG. 1 is a cross-sectional side view of one embodiment of the inventionhaving a containment case containing a locking mechanism of theinvention in an armed condition;

FIGS. 2 and 3 are views similar to FIG. 1 showing the needle withdrawninto the containment case and the locking mechanism engaged with theneedle, positioned to prevent further withdrawal of the needle tip fromthe containment case or reemergence of the needle tip, respectively;

FIG. 4 is a cross-sectional side view of a second embodiment of theinvention having a containment case containing a locking mechanism andadditional reemergence barrier mounted within the case in an armedconfiguration; and

FIG. 5 is a view similar to FIG. 4 with the needle withdrawn into thecontainment case and the locking mechanism engaged with the needle.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIG. 1, a containment case 1, which may cylindrically surround aneedle 2 with a tip 3, has seated therein a strip of spring metal 4which serves to provide the locking mechanism of the invention. The baseend 5 of the strip of metal 4 is seated in a slot S in the inner wall ofthe containment case 1 with a close, sliding fit to allow for slightdisplacement of base end 5. A locking plate portion 6 of the strip 4 hasan aperture 7 such as a hole through which needle 2 projects. Strip 4and plate 6 may be a single piece of metal strip. Alternatively, lockingplate portion 6 may be in the form of a hardened steel plate that isspot-welded to thinner spring-sheld strip 4. Hole 7 is dimensioned toprovide a close sliding fit with needle 2 when the device is in thearmed condition shown in FIG. 1. The strip 4 extends with a sensing armsegment or sensing arm 8 with a sensing end 9. The sensing arm 8 may bestiffened by a flange, as by being of “L” shape in cross-section.

Extending from the sensing end 9 is a sensing means 10 which hooks underthe needle 2. The sensing means 10 may be the lower portion of a platewhich extends downwardly from the sensing end 9, such plate having ahole or slot cut into it (seen in FIG. 2), or may simply be a fingerwhich extends under the needle 2.

A curved portion 11 of the strip 4 is spring-loaded, biasing the lockingplate portion 6 to seek to rotate in a clockwise direction in theconfiguration as shown in FIG. 1. Curved portion 11 of strip 4 biaseslocking plate portion 6 for rotation, and so portion 11 can be made ofthinner spring or other like metal with plate portion 6 being of thickerand harder material.

When the needle tip 3 is withdrawn to the right into the containmentcase 1 past the sensing means 10 as shown in FIG. 2, the sensing means10 is released to rotate clockwise and upwardly under the urging of thecurved, spring-loaded portion 11. The sensing arm 8 also rises upwardly,rotating in the clockwise direction as well. Adjacent inner wall 29 ofcase 1 may be shaped to conform to the path of travel of end 9 assensing arm 8 swings upwardly. That upward swinging motion, in turn,urges the locking plate 6 to rotate in a clockwise direction. Because ofthe close sliding fit between the needle 2 and hole 7, rotation of thelocking plate 6 is almost immediately arrested. Also, base end 5 maydisplace within slot 6 leaving a small gap S_(G) as seen in FIG. 2 asstrip 4 is carried with needle 2.

A first buttressing surface 12 on the inner surface of the case 1receives the lower end 13 of the locking plate portion 6 of the strip 4.Further attempts to withdraw the needle 2 from the case 1 (to the rightin FIG. 3) urge the locking plate 6 to rotate further in the clockwisedirection. Due to the adjacent edges of the hole 7 engaging with thesurface of the needle 2, substantial actual rotation does not takeplace, but the locking plate 6 locks firmly into place on the surface ofthe needle 2, thus preventing further withdrawal of needle 2 from case1.

When an attempt is made to advance the needle 2 for reemergence from thecase 1, which would be to the left as shown in FIG. 3, the now upwardlyrotated sensing arm 8 is carried forward within the case 1 until theupper portion 14 and end 9 of the sensing arm 8 abut against a secondabutment 15 on the interior of the case 1. Simultaneously, the base end5 of the strip 4 may shift forward into gap S_(G). Any further attemptat advancement of the needle 2 to the left for reemergence from the case1 applies a force to the upper end 16 of the locking plate 6. Aspreviously, this urges the locking plate 6 to rotate, to thereby effecta further locking engagement with the needle 2. Second abutment 15 isadvantageously defined within notch or recess 25 and may present areceding face to end 9. Also, slot S may alternatively open upwardlyinto case 1 as depicted, for sake of convenience, in only FIG. 3, withthe sidewalls 26 (only one shown) of slot S providing confinement toorient strip 4 to ensure that end 9 is aligned with abutment surface 15.

When the upper portion 14 of the sensing arm 8 first rises to itsrotated orientation as shown in FIG. 2, it becomes aligned with secondabutment 15. Notch or recess 25 may be in the form of a circumferentialgroove following the curvature of the confinement case 1 thereat tofacilitate the desired alignment. Additionally, the first abutment 12may carry a resilient member 17, such as a resilient pad or coiledspring (the latter not shown), that serves to assist in shifting thebase end 5 forwardly in its slot and to maintain a rotational bias oflocking plate 6 towards engagement with needle 2.

The motion depicted in FIG. 3 whereby the upper portion 14 and end 9 ofthe sensing arm 8 has shifted into abutting contact against the secondabutment 15 is minimal. The resilient member 17 at the location of thefirst abutment 12 helps ensure that the lower end of the locking plate13 is carried forwardly during this slight advancement of the needle,retaining the locking plate 6 in its locking orientation. This furtherensures that the locking plate 6 is urged to rotate to effect thefurther locking engagement with the needle 2. Where member 17 is aresilient pad, the pad may be comprised of resilient polymeric material.

While the needle guard as described in FIGS. 1 to 3 is locked in placeagainst movement of the needle 2, to prevent further withdrawal orreemergence of the needle tip 3 from the case 1, a supplementalreemergence barrier 20 may be provided as seen in FIGS. 4 and 5. Thisbarrier is provided by a second spring-biased strip 21 seated at itsbase end in a slot 22 within the inner surface of the case 1. At theother end of this second strip 21, a barrier plate 23 is provided with asensing end 27.

In FIG. 4, the sensing end 27 bears against the side of the needle 2. InFIG. 5 the needle tip 3 has been withdrawn past the sensing end 27,whereupon the spring bias within the strip 21 causes the reemergencebarrier plate 23 to rise into the path of the needle 2. Any attempt toadvance the needle thereafter for reemergence will be arrested by thereemergence barrier plate 23.

In this manner, extra security may be provided against the reemergenceof the needle tip 3 from the case 1.

While the present invention has been illustrated by the description ofembodiments thereof, and while the embodiments have been described inconsiderable detail, it is not intended to restrict or in any way limitthe scope of the appended claims to such detail. Additional advantagesand modifications will readily appear to those skilled in the art. Theinvention in its broader aspects is therefore not limited to thespecific details, representative apparatus and methods and illustrativeexamples shown and described. Accordingly, departures may be made fromsuch details without departing from the scope or spirit of the generalinventive concept.

1. A protective device for a needle having a needle tip and a needleshaft, said device comprising: a containment case having a cavitytherein through which a needle is received; a canting plate within saidcavity, said plate having a hole through which the needle is received,said hole having an inner face surface bounded by first and secondcircumferential edges that provide a close sliding fit around theneedle; a sensing arm coupled to the canting plate to align thecircumferential edges for sliding engagement with the needle while theneedle tip protrudes from the containment casing; resilient biasingmeans acting between the casing and the sensing arm and canting plate tocause the canting plate to rotate with respect to the needle uponwithdrawal of the needle tip into the containment cavity; a sensing limbon the sensing arm that contacts the shaft of the needle before theneedle is withdrawn into the containment cavity, restraining the sensingarm and canting plate from rotating so long as the sensing limb remainsin contact with the shaft of the needle, but permitting such rotation,once the sensing limb ceases to be in contact with the shaft of theneedle; first and second pressure points present on the canting plateand sensing arm; first and second abutment means present and carriedwithin the cavity of the containment case; wherein the canting plate andsensing arm are aligned within the cavity for respective contact betweensaid first and second pressure points and said first and second abutmentmeans, the first pressure point being positioned to engage with thefirst abutment means upon withdrawal of the needle tip into the needleguard cavity, such engagement effecting the canting of the cantingplate, and the second pressure point being positioned to engage with thesecond abutment means once the canting late has assumed a cantedorientation whereby, upon any attempt to further retract the needle fromthe needle guard, the canting of the canting plate causes the first andsecond circumferential edges bounding the hole in the canting plate tobe directed into locking engagement with the surface of the needleshaft, and, upon any attempt to cause reemergence of the needle tip fromthe needle guard, contact between the second pressure point and secondabutment means tends to rotate the canting plate so as to further engagethe circumferential edges with the surface of the needle shaft, tothereby lockingly contain the needle tip within the containment case ofthe needle guard against either further withdrawal of the needle orreemergence of the needle tip.
 2. The protective device of claim 1wherein the sensing arm comprises a limb that bears against the needleshaft while the needle tip protrudes from the containment casingpreventing the canting plate from rotating with respect to the needle solong as the limb on the sensing arm bears against the needle shaft,which limb, upon retraction of the needle tip past this limb, becomesfree to rotate, allowing the canting plate to take up a cantingorientation that permits locking engagement of the needle guard with theneedle.
 3. The protective device of claim 2 wherein the limb on thesensing arm comprises a plate with a hole positioned and dimensioned toreceive the needle therethrough before the needle is withdrawn into theneedle guard.
 4. The protective device of claim 2 wherein the limb onthe sensing arm comprises a plate with a slot positioned and dimensionedto receive the needle therethrough before the needle is withdrawn intothe needle guard.
 5. The protective device of claim 2 wherein the limbon the sensing arm comprises a finger that prevents displacement of thelimb and sensing arm so long as the finger bears against the needleshaft.
 6. The protective device of claim 1, the canting plate beingshiftable with respect to the containment case in both longitudinaldirections of the needle.
 7. The protective device of claim 1 furthercomprising a resilient member positioned to bias the canting plate atone end for displacement towards the needle tip.
 8. A protective devicefor a needle having a needle tip and a needle shaft, said devicecomprising: a containment case having a cavity through which a needle isreceived; a canting plate within said cavity, said plate having a holethrough which the needle is received, said hole having an inner facesurface bounded by first and second circumferential edges that provide aclose sliding fit around the needle, the canting plate being shiftablewith respect to the containment case in both longitudinal directions ofthe needle; a sensing arm coupled to the canting plate to align thecircumferential edges for sliding engagement with the needle while theneedle tip protrudes from the containment casing; resilient biasingmeans acting between the casing and the sensing arm and canting plate tocause the canting plate to rotate with respect to the needle uponwithdrawal of the needle tip into the containment cavity; a sensing limbon the sensing arm that contacts the shaft of the needle before theneedle is withdrawn into the containment cavity, restraining the sensingarm and canting plate from rotating so long as the sensing limb remainsin contact with the shaft of the needle, but permitting such rotation,once the sensing limb ceases to be in contact with the shaft of theneedle; first and second pressure points present on the canting plateand sensing arm; first and second abutment means present and carriedwithin the cavity of the containment case; a resilient member positionedto bias the canting plate at one end for displacement towards the needletip; wherein the canting plate and sensing arm are aligned within thecavity for respective contact between said first and second pressurepoints and said first and second abutment means, the first pressurepoint being positioned to engage with the first abutment means uponwithdrawal of the needle tip into the needle guard cavity, suchengagement effecting the canting of the canting plate, and the secondpressure point being positioned to engage with the second abutment meansonce the canting late has assumed a canted orientation whereby, upon anyattempt to further retract the needle from the needle guard, the cantingof the canting plate causes the first and second circumferential edgesbounding the hole in the canting plate to be directed into lockingengagement with the surface of the needle shaft, and, upon any attemptto cause reemergence of the needle tip from the needle guard, contactbetween the second pressure point and second abutment means tends torotate the canting plate so as to further engage the circumferentialedges with the surface of the needle shaft, to thereby lockingly containthe needle tip within the containment case of the needle guard againsteither further withdrawal of the needle or reemergence of the needletip.
 9. The protective device of claim 8 wherein the sensing armcomprises a limb that bears against the needle shaft while the needletip protrudes from the containment casing preventing the canting platefrom rotating with respect to the needle so long as the limb on thesensing arm bears against the needle shaft, which limb, upon retractionof the needle tip past this limb, becomes free to rotate, allowing thecanting plate to take up a canting orientation that permits lockingengagement of the needle guard with the needle.
 10. The protectivedevice of claim 9 wherein the limb on the sensing arm comprises a platewith a hole positioned and dimensioned to receive the needletherethrough before the needle is withdrawn into the needle guard. 11.The protective device of claim 9 wherein the limb on the sensing armcomprises a plate with a slot positioned and dimensioned to receive theneedle therethrough before the needle is withdrawn into the needleguard.
 12. The protective device of claim 9 wherein the limb on thesensing arm comprises a finger that prevents displacement of the limband sensing arm so long as the finger bears against the needle shaft.13. The protective device of claim 8 wherein the resilient membercomprises a pad.